Today, vehicles feature numerous safety, body and powertrain applications that rely on magnetic position and/or angle sensors. For example, in Electric Power Steering (EPS), magnetic angle sensors and linear Hall sensors can be used to measure steering angle and steering torque. Modern powertrain systems can rely on magnetic speed sensors for camshaft, crankshaft and transmission applications, along with automotive pressure sensors, to achieve required CO2 targets and smart powertrain solutions.
In the field of speed sensing, a sinusoidal signal may be generated by a magnetic sensor in response to a rotation of a target object, such as a wheel, camshaft, crankshaft, or the like. The sinusoidal signal may be translated into pulses, which is further translated into a movement detection or a speed output. Both anti-lock braking system (ABS) applications and transmission applications, for example, have a trend for requiring more pulses per revolution for increased accuracy. In both ABS and transmission applications it is desired that the number of pulses per revolution be increased by a factor 2, 4, or even higher.
In the field of position sensing, in a similar sense, sinusoidal signals may be used to calculate accurate angle information, for example, for steering wheel position sensing. For position sensing, a higher degree of resolution is desired.
Currently, higher accuracy requirements in speed sensing applications may be realized with an increase of number of poles or teeth on a target object. However, the number of poles or teeth on a target object depends on the object diameter and, in general, there is a technical limit to the minimum size of a single pole or tooth. In addition, the higher the number of pole pairs or tooth/notches, the higher the manufacturing costs. Thus, increasing the numbers of poles or teeth relates in a trade of between cost and accuracy. In addition, an increase in the number of poles or teeth may also increase bandwidth requirements.
Therefore, an improved sensing device without increasing the number or poles or teeth of a sensing target may be desirable.